This invention relates to formulations and methods for enhancing the efficacy of exogenous chemicals used in treating plants. An exogenous chemical, as defined herein, is any chemical substance, whether naturally or synthetically derived, which (a) has biological activity or is capable of releasing in a plant an ion, moiety or derivative which has biological activity, and (b) is applied to a plant with the intent or result that the chemical substance or its biologically active ion, moiety or derivative enter living cells or tissues of the plant and elicit a stimulatory, inhibitory, regulatory, therapeutic, toxic or lethal response in the plant itself or in a pathogen, parasite or feeding organism present in or on the plant. Examples of exogenous chemical substances include, but are not limited to, chemical pesticides (such as herbicides, algicides, fungicides, bactericides, viricides, insecticides, aphicides, miticides, nematicides, molluscicides, and the like), plant growth regulators, fertilizers and nutrients, gametocides, defoliants, desiccants, mixtures thereof, and the like.
Exogenous chemicals including foliar-applied herbicides, have at times been formulated with surfactants, so that when water is added, the resulting sprayable composition is more easily and effectively retained on the foliage (e.g., the leaves or other photosynthesizing organs) of plants. Surfactants can also bring other benefits, including improved contact of spray droplets with a waxy leaf surface and, in some cases, improved penetration of the accompanying exogenous chemical into the interior of leaves. Through these and perhaps other effects, surfactants have long been known to increase the biological effectiveness of herbicide compositions, or other compositions of exogenous chemicals, when added to or included in such compositions. Thus, for example, the herbicide glyphosate (N-phosphonomethylglycine) has been formulated with surfactants such as polyoxyalkylene-type surfactants including, among other surfactants, polyoxyalkylene alkylamines. Commercial formulations of glyphosate herbicide marketed under the trademark ROUNDUP(copyright) have been formulated with a surfactant composition based on such a polyoxyalkylene alkylamine, in particular a polyethoxylated tallowamine, this surfactant composition being identified as MON 0818. Surfactants have generally been combined with glyphosate or other exogenous chemicals either in a commercial concentrate (herein referred to as a xe2x80x9ccoformulationxe2x80x9d), or in a diluted mixture that is prepared from separate compositions, one comprising an exogenous chemical (e.g. glyphosate) and another comprising surfactant, prior to use in the field (i.e., a tank mix).
Various combinations of exogenous chemicals and surfactants or other adjuvants have been tested in the past. In some instances, the addition of a particular surfactant has not produced uniformly positive or negative changes in the effect of the exogenous chemical on the plant (e.g., a surfactant that may enhance the activity of a particular herbicide on certain weeds may interfere with, or antagonize, the herbicidal efficacy on another weed species).
Some surfactants tend to degrade fairly rapidly in aqueous solutions. As a result, surfactants that exhibit this property can only be used effectively in tank mixes (i.e., mixed with the other ingredients in solution or dispersion in the tank soon before spraying is to occur), rather than being coformulated in an aqueous composition with the other ingredients in the first instance. This lack of stability, or inadequate shelf-life, has hindered the use of certain surfactants in some exogenous chemical formulations.
Other surfactants, though chemically stable, are physically incompatible with certain exogenous chemicals, particularly in concentrate coformulations. For example, most classes of nonionic surfactant, including polyoxyethylene alkylether surfactants, do not tolerate solutions of high ionic strength, as for example in a concentrated aqueous solution of a salt of glyphosate. Physical incompatibility can also lead to inadequate shelf-life. Other problems that can arise from such incompatibility include the formation of aggregates large enough to interfere with commercial handling and application, for example by blocking spray nozzles.
Another problem that has been observed in the past is the effect of environmental conditions on uptake of an exogenous chemical composition into foliage of a plant. For example, conditions such as temperature, relative humidity, presence or absence of sunlight, and health of the plant to be treated, can affect the uptake of a herbicide into the plant. As a result, spraying exactly the same herbicidal composition in two different situations can result in different herbicidal control of the sprayed plants.
One consequence of the above-described variability is that often a higher rate of herbicide per unit area is applied than might actually be required in that situation, in order to be certain that adequate control of undesired plants will be achieved. For similar reasons, other foliar-applied exogenous chemicals are also typically applied at significantly higher rates than needed to give the desired biological effect in the particular situation where they are used, to allow for the natural variability that exists in efficiency of foliar uptake. A need therefore exists for compositions of exogenous chemicals that, through more efficient uptake into plant foliage, allow reduced use rates.
Many exogenous chemicals are commercially packaged as a liquid concentrate that contains a significant amount of water. The packaged concentrate is shipped to distributors or retailers. Ultimately the packaged concentrate ends up in the hands of an end user, who further dilutes the concentrate by adding water in accordance with label instructions on the package. The fully diluted material is then sprayed on plants.
A significant portion of the cost of such packaged concentrates is the cost of transporting the concentrate from the manufacturing site to the location where the end user purchases it. Any liquid concentrate formulation that contained relatively less water and thus more exogenous chemical would reduce the cost per unit amount of exogenous chemical. However, one important limit on the ability of the manufacturer to increase the loading of the exogenous chemical in the concentrate is the stability of that formulation. With some combinations of ingredients, a limit will be reached at which any further reduction of water content in the concentrate will cause it to become unstable (e.g., to separate into discrete layers), which may make it commercially unacceptable.
Accordingly, a need exists for improved formulations of exogenous chemicals, particularly herbicides, that are stable, effective, less sensitive to environmental conditions, and permit the use of reduced amounts of exogenous chemical to achieve the desired biological effect in or on plants. A need also exists for stable liquid concentrate formulations of exogenous chemicals that contain less water and more exogenous chemical than prior art concentrates.
The present invention relates to novel methods and compositions wherein exogenous chemicals are applied to plants to generate a desired biological response.
One embodiment of the present invention is a plant treatment composition that comprises (a) an exogenous chemical; (b) a first excipient substance which is a compound or mixture of compounds having the formula
R14xe2x80x94COxe2x80x94Axe2x80x94R15xe2x80x83xe2x80x83VII
wherein R14 is a hydrocarbyl group having about 5 to about 21 carbon atoms, R15 is a hydrocarbyl group having 1 to about 14 carbon atoms, the total number of carbon atoms in R14 and R15 is about 11 to about 27, and A is O or NH; and (c) a second excipient substance which is an amphiphilic substance having a critical packing parameter greater than ⅓.
In one preferred embodiment, the weight/weight ratio of second excipient substance to the exogenous chemical is from about 1:3 to about 1:100. It is particularly preferred that the weight/weight ratio of first excipient substance to the exogenous chemical is also from about 1:3 to about 1:100. In another embodiment, R14 is saturated in from about 40 to 100 percent by weight of all compounds having the stated formula present in the composition. In another embodiment, R14 has about 11 to about 21 carbon atoms, R15 has 1 to about 6 carbon atoms and A is O.
In certain preferred embodiments of the present invention, the first excipient substance is a C1-4 alkyl ester of a C12-18 fatty acid, more preferably a C1-4 alkyl ester of a C12-18 saturated fatty acid. Propyl, isopropyl or butyl esters of C12-18 fatty acids, such as butyl stearate, are especially preferred.
A wide variety of exogenous chemicals can be used in the compositions and methods of the present invention. A preferred class is foliar-applied exogenous chemicals, i.e. exogenous chemicals that are normally applied post-emergence to foliage of plants. A preferred subclass of foliar-applied exogenous chemicals is those that are water-soluble. Especially preferred water-soluble exogenous chemicals are those that have an anion portion and a cation portion. In one embodiment of the invention, at least one of the anion and cation portions is biologically active and has a molecular weight of less than about 300. Particular examples of such exogenous chemicals where the cation portion is biologically active are paraquat, diquat and chlormequat. More commonly it is the anion portion that is biologically active.
Another preferred subclass of exogenous chemicals is those that exhibit systemic biological activity in the plant. Within this subclass, an especially preferred group of exogenous chemicals is N-phosphonomethylglycine and its herbicidal derivatives. N-phosphonomethylglycine, often refereed to by its common name glyphosate, can be used in its acid form, but is more preferably used in the form of a salt. Any water-soluble salt of glyphosate can be used in the practice of this invention. Some preferred salts include the sodium, potassium, ammonium, mono-, di-, tri- and tetra-C1-4-alkylammonium, mono-, di- and tri-C1-4-alkanolammonium, mono-, di- and tri-C1-4-alkylsulfonium and sulfoxonium salts. The ammonium, monoisopropylammonium and trimethylsulfonium salts of glyphosate are especially preferred. Mixtures of salts can also be useful in certain situations.
Compositions of the present invention can be used in methods of treating plants. Foliage of a plant is contacted with a biologically effective amount of the composition. xe2x80x9cContactingxe2x80x9d in this context means placing the composition on the foliage.
A composition of the present invention comprising an exogenous chemical and a first excipient substance as described above can have a number of different physical forms. For example, the composition can further comprise water in an amount effective to make the composition a dilute aqueous composition ready for application to foliage of a plant. Alternatively, the composition can be a shelf-stable concentrate composition comprising the exogenous chemical substance in an amount of about 10 to about 90 percent by weight. Such shelf-stable concentrates can be, for example, (1) a solid composition comprising the exogenous chemical substance in an amount of about 30 to about 90 percent by weight, such as a water-soluble or water-dispersible granular formulation, or (2) a composition that further comprises a liquid diluent, wherein the composition comprises the exogenous chemical substance in an amount of about 10 to about 60 percent by weight. In this latter embodiment, it is especially preferred for the exogenous chemical substance to be water-soluble and present in an aqueous phase of the composition in an amount of about 15 to about 45 percent by weight of the composition. In this embodiment the first excipient substance is present predominantly in an oil phase of the composition, such composition typically being in the form of an emulsion, which can more specifically be, for example, an oil-in-water emulsion, a water-in-oil emulsion, or a water-in-oil-in-water multiple emulsion. In one particular embodiment of the invention, the solid or aqueous composition further comprises a solid inorganic particulate colloidal material.
As described above, one embodiment of the invention is a sprayable composition that comprises an exogenous chemical, an aqueous diluent, and a first excipient substance. The term xe2x80x9cspray compositionxe2x80x9d is sometimes used herein to mean a sprayable composition.
In a related embodiment of the invention, a concentrate composition is provided which, upon dilution, dispersion or dissolution in water forms the sprayable composition just described. The concentrate composition contains a reduced amount of the aqueous diluent, or, in a particular embodiment, is a dry composition having less than 5% water by weight. Typically a concentrate composition of the invention contains at least 10% by weight of the exogenous chemical, preferably at least 15%.
An alternative embodiment is a composition that does not itself comprise an exogenous chemical, but is intended for application to a plant in conjunction with or as a carrier for the application of an exogenous chemical. This composition comprises a first excipient substance and a second excipient substance as described above. Such a composition may be sprayable, in which case it also comprises an aqueous diluent, or it may be a concentrate, requiring dilution, dispersion or dissolution in water to provide a sprayable composition. Thus, this embodiment of the invention can be provided as a stand-alone product and applied to a plant, diluted as appropriate with water, simultaneously with the application of an exogenous chemical (for example in tank mix with the exogenous chemical), or before or after the application of the exogenous chemical, preferably within about 96 hours before or after application of the exogenous chemical.
In all embodiments, it is believed that the second excipient substance forms supramolecular aggregates in aqueous solution or dispersion. In particular it is believed that aqueous compositions of the present invention form aggregates in aqueous solution or dispersion the majority of which are not simple micelles. xe2x80x9cMajorityxe2x80x9d means that more than 50% by weight of the second excipient substance present is in the form of complex aggregates other than simple micelles, e.g. as bilayers or multilamellar structures. Preferably, more than 75% by weight is in the form of complex aggregation other than simple micelles.
Whether or not an amphiphilic substance forms such aggregates depends on its molecular architecture. The effects of molecular architecture of supramolecular self-assembly of amphiphilic molecules, as set forth for example by J. N. Israelachvili, D. J. Mitchell and B. W. Ninham in Faraday Transactions II, Volume 72, pp. 1525-1568 (1976) and in numerous later articles and monographs, are well known and understood. An important aspect is xe2x80x9ccritical packing parameterxe2x80x9d (P) which is defined in the literature by the following equation:
P=V/lA
where V is the volume of the hydrophobic tail of the molecule, l is the effective length of the hydrophobic tail, and A is the area occupied by the hydrophilic headgroup. These dimensions can be calculated from physical measurements as described in the literature and have been published for numerous amphiphilic compounds.
Amphiphilic substances useful as the second excipient substance herein have a critical packing parameter greater than ⅓. The second excipient substance forms aggregates in aqueous solution or dispersion which preferably have at least one dimension that is greater than two times the molecular length of the second excipient substance.
In one embodiment of the invention, the second excipient substance is a liposome-forming material. One class of liposome-forming material is an amphiphilic compound or mixture of such compounds, preferably having two hydrophobic moieties, each of which is a saturated alkyl or acyl group having from about 8 to about 22 carbon atoms. The amphiphilic compound or mixture of such compounds having said two hydrophobic moieties with about 8 to about 22 carbon atoms preferably constitutes from about 40 to 100 percent by weight of all amphiphilic compounds having two hydrophobic moieties present in the liposome-forming material. Preferably, the liposome-forming material has a hydrophilic head group comprising a cationic group. More preferably, the cationic group is an amine group.
In a preferred embodiment of the invention, the second excipient substance comprises a liposome-forming compound having a hydrophobic moiety comprising two independently saturated or unsaturated hydrocarbyl groups R1 and R2 each independently having about 7 to about 21 carbon atoms. A number of subclasses of such liposome-forming compounds are known.
One subclass has the formula
N+(CH2R1)(CH2R2)(R3)(R4)Zxe2x88x92xe2x80x83xe2x80x83I
wherein R3 and R4 are independently hydrogen, C1-4 alkyl or C1-4 hydroxyalkyl and Z is a suitable agriculturally acceptable anion.
A second subclass has the formula
N+(R5)(R6)(R7)CH2CH(OCH2R1)CH2(OCH2R2)Zxe2x88x92xe2x80x83xe2x80x83II
wherein R5, R6 and R7 are independently hydrogen, C1-4 alkyl or C1-4 hydroxyalkyl and Z is a suitable anion.
A third subclass has the formula
N+(R5)(R6)(R7)CH2CH(OCOR1)CH2(OCOR2)Zxe2x88x92xe2x80x83xe2x80x83III
wherein R5, R6, R7 and Z are as defined above.
A fourth subclass has the formula
N+(R5)(R6)(R7)CH2CH2OPO(Oxe2x88x92)OCH2CH(OCOR1)CH2(OCOR2)xe2x80x83xe2x80x83IV
wherein R5, R6, and R7 are as defined above.
Compounds of formulas I-IV will have the indicated formulas in an acid medium, for example at a pH of 4 and may have the same formulas at other pH""s as well. It should be understood, however, that compositions of the present invention are not limited to use at a pH of 4.
It is preferred that about 40-100 percent of the R1 and R2 groups in the second excipient substance are saturated straight chain alkyl groups having about 7 to about 21 carbon atoms. Examples of suitable agriculturally acceptable anions Z include hydroxide, chloride, bromide, iodide, sulfate, phosphate and acetate.
In all of the above subclasses of liposome-forming substances, the hydrophilic moiety comprises a cationic group, specifically an amine or ammonium group. The compound as a whole is in some cases cationic (as in I, II and III) and in some cases neutral (as in IV). Where the amine group is quaternary, it behaves as a cationic group independently of pH. Where the amine group is secondary or tertiary, it behaves as a cationic group when protonated, i.e. in an acid medium, for example at a pH of 4.
Other subclasses of liposome-forming substances having two hydrophobic chains each comprising a C7-21 hydrocarbyl group can also be used as the second excipient substance in compositions of the invention. While substances having a cationic group in the hydrophilic moiety are preferred, nonionic or anionic substances can be used if desired.
In another embodiment, the second excipient substance is a phospholipid selected from the group consisting of di-C8-22-alkanoylphosphatidylcholines and di-C8-22-alkanoylphosphatidylethanolamines. In a particular preferred embodiment, the first excipient substance is a dipalmitoyl or distearoyl ester of phosphatidylcholine or a mixture thereof.
In a further embodiment of the invention, the second excipient substance is an alkylether surfactant or mixture of such surfactants having the formula
R12xe2x80x94Oxe2x80x94(CH2CH2O)n(CH(CH3)CH2O)mxe2x80x94R13xe2x80x83xe2x80x83VI
wherein R12 is an alkyl or alkenyl group having about 16 to about 22 carbon atoms, n is an average number of about 10 to about 100, m is an average number of 0 to about 5 and R13 is hydrogen or C1-4 alkyl. The term xe2x80x9calkyletherxe2x80x9d as used herein should be understood to include alkenylether surfactants. Preferably R12 is a saturated straight-chain alkyl group, R13 is hydrogen, m is 0 and n is from about 20 to about 40. Most preferably the alkylether surfactant is a polyoxyethylene cetyl or stearyl ether or mixture thereof having 20-40 moles of ethylene oxide (EO).
Aqueous compositions of the present invention can comprise supramolecular aggregates formed from the first and/or second excipient substances. In one preferred embodiment, the second excipient substance is a vesicle-forming amphiphilic substance, such as a vesicle-forming lipid, and when the substance is dispersed in water the majority (greater than 50% by weight, preferably greater than 75% by weight) of the second excipient substance is present as vesicles or liposomes. In another preferred embodiment the second excipient substance is present as bilayers or multilamellar structures which are not organized as vesicles or liposomes. Compositions of the present invention can also include, without limitation, colloidal systems such as emulsions (water/oil, oil/water, or multiple, e.g., water/oil/water), foams, microemulsions, and suspensions or dispersions of microparticulates, nanoparticulates, or microcapsules. Compositions of the invention can include more than one type of aggregate or colloidal system; examples include liposomes or vesicles dispersed in a microemulsion, and compositions having characteristics of both emulsions and suspensions, e.g. suspo-emulsions. The present invention also encompasses any formulation, which may or may not contain a significant amount of water, that on dilution in an aqueous medium forms such colloidal systems, and/or systems comprising vesicles, liposomes, bilayers or multilamellar structures, so long as the other requirements stipulated herein are met.
The weight ratio of each of the first and second excipient substances to the exogenous chemical preferably is between about 1:3 and about 1:100. We have been surprised by the high level of biological effectiveness, specifically herbicidal effectiveness of a glyphosate composition, exhibited at such low ratios of such excipient substances to exogenous chemical. Higher ratios can also be effective but are likely to be uneconomic in most situations and increase the risk of producing an antagonistic effect on effectiveness of the exogenous chemical.
It is surprising that the enhancement of biological activity that has been observed when using the present invention can be achieved with the addition of relatively small amounts of such excipient substances.
In any of the above particular embodiments, the exogenous chemical and/or first excipient substance can be encapsulated within or associated with the aggregates (e.g., liposomes) formed by the second excipient substance, but do not necessarily have to be so encapsulated or associated. xe2x80x9cAssociatedxe2x80x9d in this context means bound to or at least partly intercalated in some fashion in a vesicle wall, as opposed to being encapsulated. In yet another embodiment of the invention, the exogenous chemical and/or first excipient substance is not encapsulated in or associated with the liposomes at all. Although the present invention does not exclude the possibility of so encapsulating or associating the exogenous chemical, a presently preferred dilute sprayable liposomal composition encapsulates less than 5% by weight of the exogenous chemical that is present in the overall composition. Another dilute sprayable liposomal embodiment of the present invention has no substantial amount (i.e., less than 1% by weight) of the exogenous chemical encapsulated in the liposomes. As a droplet of such a liposomal composition dries on foliage of a plant, the proportion of the exogenous chemical that is encapsulated in the liposomes may change.
The compositions and methods of the present invention have a number of advantages. They provide enhanced biological activity of exogenous chemicals in or on plants in comparison with prior formulations, either in terms of greater ultimate biological effect, or obtaining an equivalent biological effect while using a reduced application rate of exogenous chemical. Certain herbicide formulations of the present invention can avoid antagonism that has been observed in some prior art herbicide formulations, and can minimize quick production of necrotic lesions on leaves that in some situations hinder overall translocation of herbicide in the plant. Certain herbicide compositions of the invention modify the spectrum of activity of the herbicide across a range of plant species. For example, certain formulations of the present invention containing glyphosate can provide good herbicidal activity against broadleaf weeds while not losing any herbicidal effectiveness on narrowleaf weeds. Others can enhance herbicidal effectiveness on narrowleaf weeds to a greater extent than on broadleaf weeds. Still others can have enhanced effectiveness which is specific to a narrow range of species or even a single species.
Another advantage of the present invention is that it employs relatively small amounts of the first and second excipient substances in relation to the amount of exogenous chemical employed. This makes the compositions and methods of the present invention relatively inexpensive, and also tends to reduce instability problems in specific compositions where one or both excipient substances are physically incompatible with the exogenous chemical (e.g., alkylether surfactants in solutions of high ionic strength, such as concentrated glyphosate salt solutions).
Even at the low concentrations of the excipient substances used in the present invention, there may be limits on the maximum concentration of exogenous chemical that can be used without causing compatibility problems (e.g., separation of the composition into discrete layers). In some preferred embodiments of the invention, composition stability at high loadings of exogenous chemical is maintained by adding other ingredients such as, for example, colloidal particulates. Some compositions of the present invention exhibit enhanced biological activity and have a higher loading of exogenous chemical than possible in prior art compositions.
Further, compositions of the present invention are less sensitive in some instances to environmental conditions such as relative humidity at the time of application to the plant. Also, the present invention allows the use of smaller amounts of herbicides or other pesticides, while still obtaining the required degree of control of weeds or other undesired organisms.
Examples of exogenous chemical substances that can be included in compositions of the present invention include, but are not limited to, chemical pesticides (such as herbicides, algicides, fungicides, bactericides, viricides, insecticides, aphicides, miticides, nematicides, molluscicides and the like), plant growth regulators, fertilizers and nutrients, gametocides, defoliants, desiccants, mixtures thereof and the like. In one embodiment of the invention, the exogenous chemical is polar.
A preferred group of exogenous chemicals are those that are normally applied post-emergence to the foliage of plants, i.e. foliar-applied exogenous chemicals.
Some exogenous chemicals useful in the present invention are water-soluble, for example salts that comprise biologically active ions, and also comprise counterions, which may be biologically inert or relatively inactive. A particularly preferred group of these water-soluble exogenous chemicals or their biologically active ions or moieties are systemic in plants, that is, they are to some extent translocated from the point of entry in the foliage to other parts of the plant where they can exert their desired biological effect. Especially preferred among these are herbicides, plant growth regulators and nematicides, particularly those that have a molecular weight, excluding counterions, of less than about 300. More especially preferred among these are exogenous chemical compounds having one or more functional groups selected from amine, carboxylate, phosphonate and phosphinate groups.
Among such compounds, an even more preferred group are herbicidal or plant growth, regulating exogenous chemical compounds having at least one of each of amine, carboxylate, and either phosphonate or phosphinate functional groups. Salts of N-phosphonomethylglycine are examples of this group of exogenous chemicals. Further examples include salts of glufosinate, for instance the ammonium salt (ammonium DL-homoalanin-4-yl (methyl) phosphinate).
Another preferred group of exogenous chemicals which can be applied by the method of the invention are nematicides such as those disclosed in U.S. Pat. No. 5,389,680, the disclosure of which is incorporated herein by reference. Preferred nematicides of this group are salts of 3,4,4-trifluoro-3-butenoic acid or of N-(3,4,4-trifluoro-1-oxo-3-butenyl)glycine.
Exogenous chemicals which can usefully be applied by the method of the present invention are normally, but not exclusively, those which are expected to have a beneficial effect on the overall growth or yield of desired plants such as crops, or a deleterious or lethal effect on the growth of undesirable plants such as weeds. The method of the present invention is particularly useful for herbicides, especially those that are normally applied post-emergence to the foliage of unwanted vegetation.
Herbicides which can be applied by the method of the present invention include but are not limited to any listed in standard reference works such as the xe2x80x9cHerbicide Handbook,xe2x80x9d Weed Science Society of America, 1994, 7th Edition, or the xe2x80x9cFarm Chemicals Handbook,xe2x80x9d Meister Publishing Company, 1997 Edition. Illustratively these herbicides include acetanilides such as acetochlor, alachlor and metolachlor, aminotriazole, asulam, bentazon, bialaphos, bipyridyls such as paraquat, bromacil, cyclohexenones such as clethodim and sethoxydim, dicamba, diflufenican, dinitroanilines such as pendimethalin, diphenylethers such as acifluorfen, fomesafen and oxyfluorfen, fatty acids such as C9-10 fatty acids, fosamine, flupoxam, glufosinate, glyphosate, hydroxybenzonitriles such as bromoxynil, imidazolinones such as imazaquin and imazethapyr, isoxaben, norflurazon, phenoxies such as 2,4-D, phenoxypropionates such as diclofop, fluazifop and quizalofop, picloram, propanil, substituted ureas such as fluometuron and isoproturon, sulfonylureas such as chlorimuron, chlorsulfuron, halosulfuron, metsulfuron, primisulfuron, sulfometuron and sulfosulfuron, thiocarbamates such as triallate, triazines such as atrazine and metribuzin, and triclopyr. Herbicidally active derivatives of any known herbicide are also within the scope of the present invention. A herbicidally active derivative is any compound which is a minor structural modification, most commonly but not restrictively a salt or ester, of a known herbicide. These compounds retain the essential activity of the parent herbicide, but may not necessarily have a potency equal to that of the parent herbicide. These compounds may convert to the parent herbicide before or after they enter the treated plant. Mixtures or coformulations of a herbicide with other ingredients, or of more than one herbicide, may likewise be employed.
An especially preferred herbicide is N-phosphonomethylglycine (glyphosate), a salt, adduct or ester thereof, or a compound which is converted to glyphosate in plant tissues or which otherwise provides glyphosate ion. Glyphosate salts that can be used according to this invention include but are not restricted to alkali metal, for example sodium and potassium, salts; ammonium salt; alkylamine, for example dimethylamine and isopropylamine, salts; alkanolamine, for example ethanolamine, salts; alkylsulfonium, for example trimethylsulfonium, salts; sulfoxonium salts; and mixtures thereof. The herbicidal compositions sold by Monsanto Company as ROUNDUP(copyright) and ACCORD(copyright) contain the monoisopropylamine (IPA) salt of N-phosphonomethylglycine. The herbicidal compositions sold by Monsanto Company as ROUNDUP(copyright) Dry and RIVAL(copyright) contain the monoammonium salt of N-phosphonomethylglycine. The herbicidal composition sold by Monsanto Company as ROUNDUP(copyright) Geoforce contains the monosodium salt of N-phosphonomethylglycine. The herbicidal composition sold by Zeneca as TOUCHDOWN(copyright) contains the trimethylsulfonium salt of N-phosphonomethylglycine. The herbicidal properties of N-phosphonomethylglycine and its derivatives were first discovered by Franz, then disclosed and patented in U.S. Pat. No. 3,799,758, issued Mar. 26, 1974. A number of herbicidal salts of N-phosphonomethylglycine were patented by Franz in U.S. Pat. No. 4,405,531, issued Sep. 20, 1983. The disclosures of both of these patents are hereby incorporated by reference.
Because the commercially most important herbicidal derivatives of N-phosphonomethylglycine are certain salts thereof, the glyphosate compositions useful in the present invention will be described in more detail with respect to such salts. These salts are well known and include ammonium, IPA, alkali metal (such as the mono-, di-, and trisodium salts, and the mono-, di-, and tripotassium salts), and trimethylsulfonium salts. Salts of N-phosphonomethylglycine are commercially significant in part because they are water soluble. The salts listed immediately above are highly water soluble, thereby allowing for highly concentrated solutions that can be diluted at the site of use. In accordance with the method of this invention as it pertains to glyphosate herbicide, an aqueous solution containing a herbicidally effective amount of glyphosate and other components in accordance with the invention is applied to foliage of plants. Such an aqueous solution can be obtained by dilution of a concentrated glyphosate salt solution with water, or dissolution or dispersion in water of a dry (e.g. granular, powder, tablet or briquette) glyphosate formulation.
Exogenous chemicals should be applied to plants at a rate sufficient to give the desired effect. These application rates are usually expressed as amount of exogenous chemical per unit area treated, e.g. grams per hectare (g/ha). What constitutes a xe2x80x9cdesired effectxe2x80x9d varies according to the standards and practice of those who investigate, develop, market and use a specific class of exogenous chemicals. For example, in the case of a herbicide, the amount applied per unit area to give 85% control of a plant species as measured by growth reduction or mortality is often used to define a commercially effective rate.
Herbicidal effectiveness is one of the biological effects that can be enhanced through this invention. xe2x80x9cHerbicidal effectiveness,xe2x80x9d as used herein, refers to any observable measure of control of plant growth, which can include one or more of the actions of (1) killing, (2) inhibiting growth, reproduction or proliferation, and (3) removing, destroying, or otherwise diminishing the occurrence and activity of plants.
The herbicidal effectiveness data set forth herein report xe2x80x9cinhibitionxe2x80x9d as a percentage following a standard procedure in the art which reflects a visual assessment of plant mortality and growth reduction by comparison with untreated plants, made by technicians specially trained to make and record such observations. In all cases, a single technician makes all assessments of percent inhibition within any one experiment or trial. Such measurements are relied upon and regularly reported by Monsanto Company in the course of its herbicide business.
The selection of application rates that are biologically effective for a specific exogenous chemical is within the skill of the ordinary agricultural scientist. Those of skill in the art will likewise recognize that individual plant conditions, weather and growing conditions, as well as the specific exogenous chemical and formulation thereof selected, will affect the efficacy achieved in practicing this invention. Useful application rates for exogenous chemicals employed can depend upon all of the above conditions. With respect to the use of the method of this invention for glyphosate herbicide, much information is known about appropriate application rates. Over two decades of glyphosate use and published studies relating to such use have provided abundant information from which a weed control practitioner can select glyphosate application rates that are herbicidally effective on particular species at particular growth stages in particular environmental conditions.
Herbicidal compositions of glyphosate or derivatives thereof are used to control a very wide variety of plants worldwide. Such compositions can be applied to a plant in a herbicidally effective amount, and can effectively control one or more plant species of one or more of the following genera without restriction: Abutilon, Amaranthus, Artemisia, Asclepias, Avena, Axonopus, Borreria, Brachiaria, Brassica, Bromus, Chenopodium, Cirsium, Commelina, Convolvulus, Cynodon, Cyperus, Digitaria, Echinochloa, Eleusine, Elymus, Equisetum, Erodium, Helianthus, Imperata, Ipomoea, Kochia, Lolium, Malva, Oryza, Ottochloa, Panicum, Paspalum, Phalaris, Phragmites, Polygonum, Portulaca, Pteridium, Pueraria, Rubus, Salsola, Setaria, Sida, Sinapis, Sorghum, Triticum, Typha, Ulex, Xanthium, and Zea.
Particularly important species for which glyphosate compositions are used are exemplified without limitation by the following:
Annual broadleaves:
velvetleaf (Abutilon theophrasti)
pigweed (Amaranthus spp.)
buttonweed (Borreria spp.)
oilseed rape, canola, indian mustard, etc. (Brassica spp.)
commelina (Commelina spp.)
filaree (Erodium spp.)
sunflower (Helianthus spp.)
morningglory (Ipomoea spp.)
kochia (Kochia scoparia)
mallow (Malva spp.)
wild buckwheat, smartweed, etc. (Polygonum spp.)
purslane (Portulaca spp.)
russian thistle (Salsola spp.)
sida (Sida spp.)
wild mustard (Sinapis arvensis)
cocklebur (Xanthium spp.)
Annual narrowleaves:
wild oat (Avena fatua)
carpetgrass (Axonopus spp.)
downy brome (Bromus tectorum)
crabgrass (Digitaria spp.)
barnyardgrass (Echinochloa crus-galli)
goosegrass (Eleusine indica)
annual ryegrass (Lolium multiflorum)
rice (Oryza sativa)
ottochloa (Ottochloa nodosa)
bahiagrass (Paspalum notatum)
canarygrass (Phalaris spp.)
foxtail (Setaria spp.)
wheat (Triticum aestivum)
corn (Zea mays)
Perennial broadleaves:
mugwort (Artemisia spp.)
milkweed (Asclepias spp.)
canada thistle (Cirsium arvense)
field bindweed (Convolvulus arvensis)
kudzu (Pueraria spp.)
Perennial narrowleaves:
brachiaria (Brachiaria spp.)
bermudagrass (Cynodon dactylon)
yellow nutsedge (Cyperus esculentus)
purple nutsedge (C. rotundus)
quackgrass (Elymus repens)
lalang (Imperata cylindrica)
perennial ryegrass (Lolium perenne)
guineagrass (Panicum maximum)
dallisgrass (Paspalum dilatatum)
reed (Phragmites spp.)
johnsongrass (Sorghum halepense)
cattail (Typha spp.)
Other perennials:
horsetail (Equisetum spp.)
bracken (Pteridium aquilinum)
blackberry (Rubus spp.)
gorse (Ulex europaeus)
Thus, the method of the present invention, as it pertains to glyphosate herbicide, can be useful on any of the above species.
Compounds useful as the first excipient substance are amides or esters of formula VII above.
R14 in formula VII is preferably aliphatic and has about 7 to about 21 carbon atoms, more preferably about 13 to about 21 carbon atoms. It is especially preferred that R14 be a saturated straight-chain alkyl group. R15 is preferably an aliphatic group having 1-6 carbon atoms, more preferably alkyl or alkenyl having 2-4 carbon atoms. An especially preferred compound of formula VII for use as the first excipient substance is butyl stearate.
As compounds of formula VII, including butyl stearate, are generally oily liquids, aqueous compositions containing them are typically emulsions having at least one aqueous phase and at least one oil phase, with the compound of formula VII being present predominantly in the oil phase. Such emulsions may be water-in-oil, oil-in-water or water-in-oil-in-water (W/O/W) multiple emulsions.
Compositions of the present invention comprise a second excipient substance which is one or more amphiphilic materials, of which two classes are preferred.
The first class of such second excipient substances can be defined as amphiphilic liposome-forming substances. These include various lipids of synthetic, animal, or plant origin, including phospholipids, ceramides, sphingolipids, dialkyl surfactants, and polymeric surfactants. A variety of these materials are known to those skilled in the art, and are commercially available. Lecithins are particularly rich in phospholipids and can be derived from a number of plant and animal sources. Soybean lecithin is one particular example of a relatively inexpensive commercially available material that includes such substances.
Many other substances have been described which can be used to form liposomes; the present invention includes compositions comprising any such liposome-forming substances, so long as other requirements set out above are met, and use of such compositions for enhancing biological effectiveness of exogenous chemicals applied to foliage of plants. For example, U.S. Pat. No. 5,580,859, incorporated here by reference, discloses liposome-forming substances having a cationic group, including N-(2,3-di-(9-(Z)-octadecenyloxy))-prop-1-yl-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-bis(oleoyloxy)-3-(trimethylammonio)propane (DOTAP). Liposome-forming substances which are not themselves cationic, but do contain a cationic group as part of the hydrophilic moiety, include for example dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE). Liposome-forming substances that do not contain a cationic group include dioleoylphosphatidylglycerol (DOPG). Any of these liposome-forming substances can be used with or without the addition of cholesterol.
These substances contain portions that are hydrophilic and hydrophobic within the same molecule. They have the ability to self-assemble in aqueous solution or dispersion into structures that are more complex than simple micelles. The nature of the aggregate that will be formed can be related to the critical packing parameter P by the following equation:
P=V/lA
where V is the volume of the hydrophobic tail of the molecule, l is the effective length of the hydrophobic tail, and A is the area occupied by the hydrophilic headgroup in the surface of the aggregate. The most probable self-assembled structures are spherical micelles when P is less than ⅓, rodlike micelles when P is between ⅓ and xc2xd, lamellar when P is between 1 and xc2xd, and inverse structures when P is greater than 1. The preferred materials in the present invention have P greater than ⅓.
Cationic liposome-forming substances having a hydrophobic moiety comprising two hydrocarbyl chains are accompanied by a counterion (anion), identified as Z in formulas I, II and III above. Any suitable anion can be used, including agriculturally acceptable anions such as hydroxide, chloride, bromide, iodide, sulfate, phosphate and acetate. In a specific embodiment where the exogenous chemical has a biologically active anion, that anion can serve as the counterion for the liposome-forming substance. For example, glyphosate can be used in its acid form together with the hydroxide of a cationic liposome-forming substance such as a compound of formula I.
Compounds of formula I known in the art to be liposome-forming include distearyldimethylammonium chloride and bromide (also known in the art as DODAC and DODAB respectively). Compounds of formula II known in the art to be liposome-forming include DOTMA referenced above and dimyristooxypropyldimethylhydroxyethylammonium bromide (DMRIE). Compounds of formula III known in the art to be liposome-forming include dioleoyloxy-3-(dimethylammonio)propane (DODAP) and DOTAP referenced above. Compounds of formula IV known in the art to be liposome-forming include DOPC and DOPE, both referenced above.
In many liposome-forming substances known in the art, the hydrophobic hydrocarbyl chains are unsaturated, having one or more double bonds. Particularly commonly used in the pharmaceutical art are dioleyl or dioleoyl compounds. A potential problem with these is that in an oxidizing environment they become oxidized at the site of the double bond. This can be inhibited by including in the formulation an antioxidant such as ascorbic acid. Alternatively the problem can be avoided by use of liposome-forming substances wherein a high proportion of the hydrophobic hydrocarbyl chains are fully saturated. Thus in a preferred embodiment of the invention. R1 and R2 in formulas I-IV are independently saturated straight-chain alkyl groups. Particularly preferred compositions use liposome-forming substances in which R1 and R2 are both palmityl (cetyl) or palmitoyl or, alternatively, are both stearyl or stearoyl groups.
Phospholipids, because of their low cost and favorable environmental properties, are particularly favored among liposome-forming substances in the method and compositions of the invention. Vegetable lecithins, such as soybean lecithin, have successfully been used in accordance with the invention. The phospholipid content of the lecithin product can range from about 10% to close to 100%. While acceptable results have been obtained with crude lecithin (10-20% phospholipid), it is generally preferred to use lecithin that is at least partially de-oiled, so that the phospholipid content is in the region of 45%. Higher grades, such as 95%, provide excellent results but the much higher cost is unlikely to be justified for most applications.
The phospholipid component of lecithin, or any phospholipid composition used in the present invention, may comprise one or more phosphatides of natural or synthetic origin. Each of these phosphatides is generally a phosphoric ester that on hydrolysis yields phosphoric acid, fatty acid(s), polyhydric alcohol and, typically, a nitrogenous base. A phosphatide component may be present in a partially hydrolyzed form, e.g. as phosphatidic acid. Suitable phosphatides include, without limitation, phosphatidylcholine, hydrogenated phosphatidylcholine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, phosphatidylglycerol, phosphatidylethanolamine, N-acyl phosphatidylethanolamine, and mixtures of any of these.
In vegetable lecithins a high proportion of the hydrophobic hydrocarbyl chains of the phospholipid compounds are typically unsaturated. One preferred embodiment of compositions in accordance with the present invention comprises both saturated phospholipid and unsaturated phospholipid, with the weight ratio of saturated phospholipid to unsaturated phospholipid being greater than about 1:2. In various particularly preferred embodiments, (1) at least 50% by weight of the phospholipids are di-C12-22-saturated alkanoyl phospholipid, (2) at least 50% by weight of the phospholipids are di-C16-18-saturated alkanoyl phospholipid, (3) at least 50% by weight of the phospholipids are distearoyl phospholipid, (4) at least 50% by weight of the phospholipids are dipalmitoyl phospholipid, or (5) at least 50% by weight of the phospholipids are distearoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or a mixture thereof. Higher proportions of saturated alkanoyl phospholipids are generally found in lecithins of animal origin, such as for example egg yolk lecithin, than in vegetable lecithins.
Phospholipids are known to be chemically unstable, at least in acid media, where they tend to degrade to their lyso-counterparts. Thus where phospholipids rather than more stable liposome-forming substances are used, it is usually preferable to adjust the pH of the composition. In the case of glyphosate compositions, the pH of a composition based on a mono-salt such as the monoisopropylammonium (IPA) salt is typically around 5 or lower. When phospholipids are used as the first excipient substance in a glyphosate composition of the invention, it will therefore be preferable to raise the pH of the composition, for example to around 7. Any convenient base can be used for this purpose; it will often be most convenient to use the same base as used in the glyphosate salt, for example isopropylamine in the case of glyphosate IPA salt.
A second class of amphiphilic substance useful as the second excipient substance according to the present invention is a long-chain alkylether surfactant having the formula VI above. R12 can be branched or unbranched, saturated or unsaturated. R12 is preferably straight-chain saturated C16 alkyl (cetyl) or straight-chain saturated C16 alkyl (stearyl). In preferred alkylethers m is 0, n is an average number from about 20 to about 40 and R12 is preferably hydrogen. Among especially preferred alkylether surfactants are those identified in the International Cosmetic Ingredient Dictionary as ceteth-20, ceteareth-20, ceteareth-27, steareth-20 and steareth-30.
Aqueous concentrate compositions in some circumstances are limited in the degree to which an exogenous chemical such as glyphosate can be loaded. At some point, as the loading of exogenous chemical is increased, the compositions will not remain suitably stable. This is particularly true, for example, where the exogenous chemical is glyphosate and the second excipient substance is an alkylether surfactant of formula VI. Addition of a small amount of colloidal particulate to such compositions has been found to greatly increase loading ability while retaining desired stability. Oxides of silicon, aluminum and titanium are preferred colloidal particulate materials. Particle size is preferably such that specific surface area is in the range from about 50 to about 400 m2/g. Where the exogenous chemical is glyphosate, the use of colloidal particulate enables loadings of at least 30% by weight for compositions containing sufficient alkylether and fatty acid ester to show enhanced herbicidal effectiveness, or at least 40% for compositions containing alkylether but no fatty acid ester, and showing herbicidal effectiveness at least equal to current commercial products loaded at about 30%. We have found especially useful improvement in storage stability can be obtained using colloidal particulates having specific surface area between about 180 and about 400 m2/g.
Other means of improving stability of highly loaded compositions may also be possible and are within the scope of the present invention.
Compositions in accordance with the present invention are typically prepared by combining water, the exogenous chemical (unless it is a formulation which will not contain an exogenous chemical) and the first and second excipient substances. Where the second excipient substance is a liposome-forming material that requires high shear to disperse in water, it is presently preferred to sonicate or microfluidize the second excipient substance in water. This can be done before or after the first excipient substance and/or the exogenous chemical is added. The sonication or microfluidization will generally produce liposomes or other aggregate structures other than simple micelles. The precise nature, including average size, of liposomes or other aggregates depends among other things on the energy input during sonication or microfluidization. Higher energy input generally results in smaller liposomes. Although it is possible to entrap or otherwise bind loosely or tightly the exogenous chemical in or on liposomes or with other supramolecular aggregates, the exogenous chemical does not need to be so entrapped or bound, and in fact the present invention is effective when the exogenous chemical is not entrapped or bound in the aggregates at all.
We have found for compositions of the present invention containing a fatty acid ester such as butyl stearate as the first excipient substance and lecithin as the second excipient substance, it is preferable to first hydrate the lecithin and then microfluidize the lecithin in water together with the fatty acid ester.
The concentrations of the various components will vary, in part depending on whether a concentrate is being prepared that will be further diluted before spraying onto a plant, or whether a solution or dispersion is being prepared that can be sprayed without further dilution.
In an aqueous glyphosate formulation that includes a C16-18 alkylether surfactant and butyl stearate, suitable concentrations can be: glyphosate 0.1-400 g a.e./l, alkylether surfactant 0.001-10% by weight, and butyl stearate 0.001-10% by weight. To achieve the higher concentrations in these ranges, it will likely be found necessary to add other ingredients to provide acceptable storage stability, for example colloidal particulate silica or aluminum oxide at 0.5-2.5% by weight. In an aqueous glyphosate formulation that includes a C16-18 alkylether surfactant but no butyl stearate, glyphosate concentration can suitably be increased to 500 g a.e./l or more, in the presence of a colloidal particulate at 0.5-2.5% by weight.
In solid glyphosate formulations, higher concentrations of ingredients are possible because of the elimination of most of the water.
Weight/weight ratios of ingredients may be more important than absolute concentrations. For example, in a glyphosate formulation containing lecithin and a fatty acid ester, the ratio of lecithin to glyphosate a.e. preferably is in the range from about 1:3 to about 1:100. It is generally preferred to use a ratio of lecithin to glyphosate a.e. close to as high as can be incorporated in the formulation while maintaining stability, in the presence of an amount of the fatty acid ester sufficient to give the desired enhancement of herbicidal effectiveness. For example, a lecithin/glyphosate a.e. ratio in the range from about 1:3 to about 1:10 will generally be found useful, although lower ratios, from about 1:10 to about 1:100, can have benefits on particular weed species in particular situations. The ratio of fatty acid ester to glyphosate a.e. is preferably in the range from about 1:3 to about 1:100, more preferably in the lower part of this range, for example from about 1:10 to about 1:100.
Where the second excipient substance is an alkylether surfactant of formula VI, a suitable weight/weight ratio of alkylether surfactant to glyphosate a.e. is again in the range from about 1:3 to about 1:100, preferably from about 1:3 to about 1:10.
The ratio of fatty acid ester to second excipient substance is preferably in the range from about 1:20 to about 5:1, more preferably in the range from about 1:15 to about 1:1, for example around 1:10. The ranges disclosed herein can be used by one of skill in the art to prepare compositions of the invention having suitable concentrations and ratios of ingredients. Preferred or optimum concentrations and ratios of ingredients for any particular use or situation can be determined by routine experimentation.
Although the combination of the components might be done in a tank mix, it is preferred in the present invention that the combination be made further in advance of the application to the plant, in order to simplify the tasks required of the person who applies the material to plants. We have found, however, that in some cases the biological effectiveness of a liposome-containing composition prepared from scratch as a dilute spray composition is superior to that of a composition having the same ingredients at the same concentrations but diluted from a previously prepared concentrate formulation.
Although various compositions of the present invention are described herein as comprising certain listed materials, in some preferred embodiments of the invention the compositions consist essentially of the indicated materials.
Optionally, other agriculturally acceptable materials can be included in the compositions. For example, more than one exogenous chemical can be included. Also, various agriculturally acceptable adjuvants can be included, whether or not their purpose is to directly contribute to the effect of the exogenous chemical on a plant. For example, when the exogenous chemical is a herbicide, liquid nitrogen fertilizer or ammonium sulfate might be included in the composition. As another example, stabilizers can be added to the composition. In some instances it might be desirable to include microencapsulated acid in the composition, to lower the pH of a spray solution on contact with a leaf. One or more surfactants can also be included. Surfactants mentioned here by trade name, and other surfactants that can be useful in the method of the invention, are indexed in standard reference works such as McCutcheon""s Emulsifiers and Detergents, 1997 edition, Handbook of Industrial Surfactants, 2nd Edition, 1997, published by Gower, and International Cosmetic Ingredient Dictionary, 6th Edition, 1995.
The compositions of the present invention can be applied to plants by spraying, using any conventional means for spraying liquids, such as spray nozzles, atomizers, or the like. Compositions of the present invention can be used in precision farming techniques, in which apparatus is employed to vary the amount of exogenous chemical applied to different parts of a field, depending on variables such as the particular plant species present, soil composition, and the like. In one embodiment of such techniques, a global positioning system operated with the spraying apparatus can be used to apply the desired amount of the composition to different parts of a field.
The composition at the time of application to plants is preferably dilute enough to be readily sprayed using standard agricultural spray equipment. Preferred application rates for the present invention vary depending upon a number of factors, including the type and concentration of active ingredient and the plant species involved. Useful rates for applying an aqueous composition to a field of foliage can range from about 25 to about 1,000 liters per hectare (l/ha) by spray application. The preferred application rates for aqueous solutions are in the range from about 50 to about 300 l/ha.
Many exogenous chemicals (including glyphosate herbicide) must be taken up by living tissues of the plant and translocated within the plant in order to produce the desired biological (e.g., herbicidal) effect. Thus, it is important that a herbicidal composition not be applied in such a manner as to excessively injure and interrupt the normal functioning of the local tissue of the plant so quickly that translocation is reduced. However, some limited degree of local injury can be insignificant, or even beneficial, in its impact on the biological effectiveness of certain exogenous chemicals.
A large number of compositions of the invention are illustrated in the Examples that follow. Many concentrate compositions of glyphosate have provided sufficient herbicidal effectiveness in greenhouse tests to warrant field testing on a wide variety of weed species under a variety of application conditions. Water-in-oil-in-water multiple emulsion compositions tested in the field have included:
The above compositions were prepared by process (vi) as described in the Examples.
Aqueous compositions tested in the field having a fatty acid ester as the first excipient substance and containing a nonionic surfactant have included:
The above compositions were prepared by process (vii) as described in the Examples.
Aqueous compositions tested in the field containing colloidal particulates have included:
The above compositions were prepared by process (ix) as described in the Examples.
Aqueous compositions tested in the field having fatty acid ester as the first excipient substance and soybean lecithin (45% phospholipid, Avanti) as the second excipient substance have included:
The above compositions were prepared by process (x) as described in the Examples.
Dry compositions tested in the field have included:
The above compositions were prepared by the process described for dry granular compositions in the Examples.